X-ray machine

An X-ray machine is a device that produces X-rays and records the shadow they cast, which lets people see inside an object or a body without cutting it open. The rays were discovered in 1895 by the German physicist Wilhelm Conrad Röntgen, and medical imaging became their best-known use. The sources reviewed for this entry credit Röntgen with the discovery but name no single inventor of the machine itself, which was refined over time by many engineers and physicians.

History of the X-ray machine

Röntgen was born in 1845 in Lennep, in Germany, and became professor of physics at the University of Würzburg in 1888. In 1895 he was studying what happens when an electric current passes through a gas at extremely low pressure inside a glass tube. Other scientists had already studied the glowing streams in such tubes, called cathode rays, including Julius Plücker, Johann Hittorf, William Crookes, Heinrich Hertz and Philipp Lenard.

On the evening of 8 November 1895, according to the Nobel Foundation, Röntgen enclosed a discharge tube in a sealed, thick black carton and worked in a dark room. A paper plate coated on one side with barium platinocyanide, a substance that glows under certain radiation, became fluorescent even when it lay as far as two meters from the tube. Something was passing through the carton.

In further experiments he found that objects of different thickness placed in the path of the rays were more or less transparent to them, and that the effect could be recorded on a photographic plate. He called the new radiation X-rays, and other scientists called them Röntgen rays.

Röntgen declined several offers of posts elsewhere, including the presidency of a national physical-technical institute in Berlin. In 1900 he moved to the University of Munich at the request of the Bavarian government, and he stayed there for the rest of his life.

In 1901 Röntgen received the first Nobel Prize in Physics. In presenting the award on 10 December 1901, the Royal Swedish Academy of Sciences described X-rays as a new form of energy that travels in straight lines like light.

Inventor and origins of the X-ray machine

Röntgen discovered X-rays, but he did not set out to create a medical device, and later machines were developed by many people. The Nobel record shows that the discovery rested on decades of earlier work on cathode rays by other physicists. His own contribution was to notice that a new kind of radiation was involved, to test its properties carefully and to show that it could make images.

The 1901 presentation speech already stressed practical uses. It noted that metals are impenetrable to X-rays while wood, leather, cardboard and muscle tissue are penetrable, so a bullet or a needle inside the body can be located with a shadow picture on a photographic plate. It also said that severe skin diseases such as lupus had been treated successfully with the rays.

How an X-ray machine works

An X-ray machine has a source that produces a beam of X-rays and a detector that records what passes through. In Röntgen’s apparatus the rays came from a discharge tube, and the detector was a photographic plate.

The US Food and Drug Administration (FDA) explains the principle for medical imaging. An X-ray beam is passed through the body, where part of it is absorbed or scattered by internal structures. The remaining pattern of X-rays reaches a detector, such as film or a computer screen, where it is recorded or processed further by a computer.

Dense structures such as bone absorb more of the beam than soft tissue, so they appear differently in the image. This is the same difference in transparency that Röntgen noticed with objects of different thickness.

Types of X-ray imaging

The FDA describes three main kinds of imaging that use X-rays. Radiography, often called a conventional X-ray, records a single image for later study. Mammography is a special type of radiography used to image the internal structures of the breast.

Fluoroscopy shows a continuous X-ray image on a monitor, so that clinicians can watch a procedure or the movement of material through the body in real time. Computed tomography, or CT, takes many X-ray measurements around the body and combines them by computer into detailed cross-sectional images. The FDA also lists dental cone-beam CT as a variant. More detail on these methods appears in the entry on X-ray imaging.

Impact and safety of X-ray machines

The FDA states that medical imaging has led to improvements in the diagnosis and treatment of many conditions in children and adults. The importance of X-rays for practical surgery was recognized from the start, because they made it possible to locate objects such as bullets and needles inside the body before an operation.

X-rays are also a form of ionizing radiation, which carries enough energy to damage DNA. The FDA says this may raise a person’s lifetime risk of developing cancer. For that reason the agency describes principles of radiation protection for health care providers, including that an exam should be justified and that exposure should be optimized, and it sets requirements for manufacturers of X-ray equipment.

The FDA also publishes rules and guidance for industry. These include electronic product radiation control requirements for manufacturers and assemblers, and medical device requirements for makers of X-ray imaging equipment.

The World Health Organization notes that medical devices, including X-ray machines and CT scanners, are today the most common human-made sources of ionizing radiation. This entry is general background and not medical advice.

Uses of X-ray machines today

Most X-ray machines are used in medicine and dentistry to diagnose injuries and disease. Radiography, fluoroscopy, mammography and CT each answer different clinical questions.

Röntgen’s discovery also opened the way for other fields. The same ability to look inside opaque objects without damaging them is used in science and industry, and the physics of X-rays remains central to the study of atoms and materials.

This entry explains a medical term. It is not medical advice. If you are concerned about your health, speak with a qualified health professional.

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 4, 2026Researched and drafted with AI assistanceReport an issue